My thanks to Fernando Escribano, who revealed the tunnels of Turin to me, and who is always "on duty" when his friends need him.
I owe a debt of gratitude also to Gian Maria Nicastro, who has been my guide to the secrets of Turin, his city. He has been my eyes in the city and has generously and swiftly provided me with any information I've asked for.
Carmen Fernandez de Bias and David Trias believed in the novel. Thank you.
And thanks, too, to Olga, the friendly voice at Random House Mondadori.